The purpose of this observational study is to identify and measure how the structural characteristics, incentives, and quality assurance efforts of managed care organizations affect quality of care among children with chronic conditions in western Washington state, specifically children with asthma, diabetes mellitus, low birthweight, and cerebral palsy. The intent of this study is to look "inside the black box of managed care" at specific features which are likely to affect the care of children with chronic conditions. We will enlist the major health plans operating in western Washington state --who cover approximately 610,000 children -- to assure the maximum variability of plan features. Features of managed care plans/products will be measured through structured interviews and document review. In this study we will define and describe these features in specific terms and develop approaches for measuring their presence and intensity. We estimate that approximately 22,000 children will be identified from health insurance claims files: 18,000 with clinically significant asthma, 1,500 with diabetes, 1,200 with cerebral palsy, and 1,780 low- birthweight infants. Claims data will be used to compute a large array of both non-categorical and condition-specific indicators of quality of care and adverse health outcomes. Because patient characteristics, disease severity, provider characteristics, and self- (or non-random) selection into plans/products or providers are likely confounders, we will collect data on these factors and test for confounding in our analyses. For this project, we will build upon our existing relationships with private health plans, Medicaid, the state's low-income health insurance plan (Basic Health Plan), and consumer groups to create a consortium/advisory board to collaborate in this study. The goal of this effort is not to identify or label any specific plan/product as either good or bad; rather our intention is to work with the plans to identify best managed care features and practices -- with the expectations that they will use this information to improve the quality of care and health outcomes for children in Washington state. We also expect that the indicators developed and used in this study will have wide interest and applicability in other settings. Furthermore, we hope that this study will help generate a greater interest in using and improving existing claims- based data systems to enhance health care monitoring and quality improvement for children with chronic conditions.